This relates generally to the manufacture of semiconductor wafers and, in particular, aspects to the patterning of such wafers.
Semiconductor wafers are processed to form integrated circuits in a highly efficient, repeatable fashion. One of the keys to semiconductor fabrication processes is the use of patterning. In a patterning process, a pattern on a mask is transferred repeatedly to wafers in a successive fashion. Generally, a lithographic system exposes a mask to radiation to transfer a pattern from the mask to a semiconductor wafer.
The wafer itself may have a photoresist which, when exposed to that radiation, changes its etch characteristics. Thus, regions exposed to radiation by the mask pattern have different etch characteristics than regions that were not exposed. Then, the photoresist may be etched to reveal the pattern in the photoresist. Thereafter, the patterned photoresist may be utilized as an etch mask to etch underlying layers.
Since there tend to be a large number of such patterning processes, the throughput of wafers through a semiconductor fabrication facility is affected by the amount of time that it takes to perform these patterning steps.
In one well known process, the degradation of the photoresist is achieved by using photoacid generators (PAGs). Thus, the efficiency of these PAGs may affect the throughput of the fabrication facility.